The present invention relates to dietary supplements and prepared foods fortified with non-esterified phytosterols that have been recrystallized with fats or oils that are essentially free of emulsifiers and the like, and to the utility of such Triglyceride-Recrystallized Phytosterols (TRPs) for reducing rancidity development in fat-containing foods, stabilizing perishable triglycerides such as those found in fish oil, and stabilizing heated fats and oils against oxidation. The present invention also relates to the surprising bioavailability of TRPs provided in the mammalian diet, resulting in a substantial decrease in plasma LDL cholesterol levels.
It has been a widely held belief that to obtain appreciable benefit from phytosterols, i.e., by definition herein, including plant sterols, stanols, or combinations thereof [including beta-sitosterol, beta-sitostanol, campesterol, campestanol, stigmasterol, stigmastanol, brassicasterol, brassicastanol, clionasterol and clionastanol (collectively termed phytosterol or phytosterols)] for lowering plasma cholesterol, the phytosterol should be dissolved in an edible oil or other solvent so that it can enter micelles in the small intestine to inhibit the absorption of cholesterol.
This belief has been supported by early research carried out in the 1950s through the 1970s showing that large doses of phytosterols in their solid form, i.e., coarse particles, were required to achieve meaningful decreases in plasma cholesterol levels. For example, in 1956, Faquhar et al., (Circulation, 14, 77-82, 1956) showed that doses of 12-18 g per day of beta sitosterol (provided in divided doses) were required to achieve a 15-20% lowering of serum cholesterol in males with atherosclerosis. In another study, 9 g per day (3 g t.i.d.) of soybean-derived phytosterols were required to lower plasma cholesterol approximately 9% (Kucchodkar et al., Atherosclerosis 23:239-248, 1976). In yet another study, 3-9 g per day of tall oil-derived phytosterols were required to lower plasma cholesterol approximately 12% (Lees et al., Atherosclerosis 28:325-333, 1977). In a recent study, 1.7 g per day of finely powdered tall oil-derived phytosterols were sufficient to lower total plasma cholesterol by 9% and LDL-cholesterol by about 15% (Jones et al., Am. J. Clin. Nutr. 69: 1144-1150, 1999).
It has been generally appreciated that phytosterols such as alpha- and beta-sitosterol, stigmosterol, campesterol and others, including the corresponding saturated (chemically reduced or hydrogenated) “stanol” species, are insoluble in water, and only slightly soluble in edible oils. Accordingly, to promote the solubilization of phytosterols, and their efficacy in lowering plasma cholesterol, U.S. Pat. No. 6,025,348 by Goto et al. describes the incorporation of at least 15% and as much as 70% by weight or more of a polyhydric alcohol/fatty acid ester (including glycerol fatty acid esters containing at least two esterified and at least one unesterified hydroxyl group such as diacylglycerols or diglycerides), into a fat. Between 1.2% and 4.7% by weight of phytosterol is incorporated into the polyhydric alcohol/fatty acid ester containing fat composition.
Perlman et al. in U.S. application Ser. No. 10/677,634, filed Oct. 1, 2003, and published as U.S. Pat. Appl. Pub. 2005-0042355, Feb. 24, 2005, describes a prepared food product which comprises an oxidation-resistant fat-based composition substantially free of exogenous solubilizing and dispersing agents for phytosterols, wherein the fat-based composition includes between 75% and 98% by weight of at least one triglyceride-based edible oil or fat, and between 2% and 25% by weight of non-esterified phytosterols in the form of triglyceride-recrystallized phytosterols (TRPs). Further discussed is a method for producing a fried snack food having reduced surface oiliness, comprising frying said snack food in a fat-based composition comprising at least one triglyceride-based edible oil or fat, and 2% to 25% by weight of non-esterified phytosterols. Further discussed are methods of preparing a TRP-containing fat-based composition comprising not more than 98% by weight of edible fat or oil and 2% to 25% by weight of non-esterified phytosterols in the form of TRPs, wherein the method comprises heating the fat-based composition for sufficient time and temperature to dissolve said non-esterified phytosterols, and cooling said composition to room temperature. Further discussed is a dietary supplement comprising at least one triglyceride-based edible fat; and between 3% and 50% by weight of triglyceride recrystallized phytosterols.
Perlman et al. in U.S. Pat. No. 6,638,547, issued Oct. 28, 2003, disclose and claim a prepared food product for ingestion by mammals, comprising an oxidation-resistant fat-based composition substantially free of exogenous solubilizing and dispersing agents for phytosterols, comprising between 75% and 98% by weight of at least one triglyceride-based edible oil or fat, between 2% and 25% by weight TRPs, wherein said fat-based composition has been partially oxidized by an interval of exposure to air, or by an interval of heating in air, and contains a reduced amount of oxidative by-products compared to a similar fat-based composition lacking said non-esterified phytosterols. Also disclosed are a reduced calorie prepared food product comprising between 75% and 98% by weight of at least one triglyceride-based edible oil or fat, between 2% and 25% by weight TRPs, wherein said non-esterified phytosterols are calorie-free and substitute for a portion of triglyceride-based edible oil or fat normally absorbed or otherwise incorporated into a prepared food product. Also disclosed are an oxidation-resistant frying or baking shortening comprising from 75% to 98% by weight of at least one edible triglyceride-based fat or oil; and from 2.0% to 25.0% by weight of TRPs. Also provided is a method for reducing plasma cholesterol levels in mammals, comprising regularly providing and ingesting a heat-processed food containing a fat-based composition comprising between 75% and 97% by weight of at least one triglyceride-based edible fat or oil, and at least 3% by weight of non-esterified TRPs, wherein the fat-based composition is substantially free of exogenous phytosterol-solubilizing and dispersing agents, and wherein said TRPs when ingested are essentially as effective as fat-soluble esterified phytosterols in reducing said plasma cholesterol levels. Also provides are methods of preparing TRP-containing fat-based compositions comprising providing a triglyceride-based edible fat-containing composition comprising between 2% and 25% by weight of non-esterified phytosterols and not more than 98% by weight of edible fat or oil, wherein said composition is substantially free of exogenous phytosterol-solubilizing and dispersing agents, heating said composition to dissolve said non-esterified phytosterols, and cooling said composition to room temperature. Also provided are methods of preparing non-esterified phytosterol-fortified prepared foods comprising providing an edible fat-based composition comprising between 2% and 25% by weight of non-esterified phytosterols and between 75% and 98% by weight of at least one edible fat or oil, wherein said composition is substantially free of exogenous phytosterol-solubilizing and dispersing agents, and other ingredients, if any, for said prepared food; cooking or otherwise heating said ingredients with said composition to allow said non-esterified phytosterols to dissolve in said oil or fat and enter or become integrated into said food product, and cooling said food product to room temperature to allow formation of triglyceride-recrystalized phytosterols (TRPs) in said composition within said prepared food.
Perlman et al. in PCT/US2002/036809, filed Nov. 14, 2002, and published as WO 2003/043433, May 30, 2003, provide a prepared food product for ingestion by mammals, comprising an oxidation-resistant fat-based composition substantially free of exogenous solubilizing and dispersing agents for phytosterols, comprising between 75% and 98% by weight of at least one triglyceride-based edible oil or fat, and between 2% and 25% by weight of non-esterified TRPs, wherein said fat-based-composition has been partially oxidized by an interval of exposure to air, or by an interval of heating in air, and contains a reduced amount of oxidative by-products compared to a similar fat-based composition lacking said non-esterified phytosterols. Further provided is a reduced calorie prepared food product comprising between 75% and 98% by weight of at least one triglyceride-based edible oil or fat, and between 2% and 25% by weight TRPs, wherein said non-esterified phytosterols are calorie-free and substitute for a portion of triglyceride-based edible oil or fat normally absorbed or otherwise incorporated into a prepared food product. Further provided is an oxidation-resistant flying or baking shortening comprising from 75% to 98% by weight of at least one edible triglyceride-based fat or oil; and from 2.0% to 25.0% by weight of TRPs. Further provided is a method for reducing plasma cholesterol levels in mammals, comprising regularly providing and ingesting a heat-processed food containing an edible fat-based composition comprising between 75% and 97% by weight of at least one triglyceride-based edible fat, and at least 3% by weight of non-esterified TRPs, wherein the fat-based composition is substantially free of exogenous phytosterol-solubilizing and dispersing agents, and wherein said TRPs when ingested are essentially as effective as fat-soluble esterified phytosterols in reducing said plasma cholesterol levels. Further provided is a method of preparing a TRP-containing fat-based composition comprising the following: providing a triglyceride-based edible fat-containing composition which in turn comprises between 2% and 25% by weight of non-esterified phytosterols and not more than 98% by weight of edible fat or oil, and wherein said composition is substantially free of exogenous phytosterol-solubilizing and dispersing agents; heating said composition to dissolve said non-esterified phytosterols; and cooling said composition to room temperature. Also provided is a method of preparing non-esterified phytosterol-fortified prepared foods comprising the following: providing an edible fat-based composition comprising between 2% and 25% by weight of non-esterified phytosterols and between 75% and 98% by weight of at least one edible fat or oil, wherein said composition is substantially free of exogenous phytosterol-solubilizing and dispersing agents, and other ingredients, if any, for said prepared food; cooking or otherwise heating said ingredients with said composition to allow said non-esterified phytosterols to dissolve in said oil or fat and enter or become integrated into said food product, and cooling said food product to room temperature to allow formation of TRPs in said composition within said prepared food.
U.S. Pat. No. 6,139,897 by Goto et al. describes an oil or fat composition containing 80% or more diacylglycerol and up to 20% phytosterol. The high proportion of diacylglycerol assures solubility or dispersal of the phytosterol to provide a cholesterol-lowering fat substitute.
U.S. Pat. No. 5,998,396 by Nakano et al., describes an edible oil containing a phytosterol, vitamin E, and an emulsifier rendering the phytosterol soluble in both the vitamin E and the edible oil.
U.S. Pat. No. 5,419,925 by Seiden et al. describes a reduced calorie fat composition based upon a substantially non-digestible polyol fatty acid polyester plus reduced calorie medium chain triglycerides and other reduced calorie fats or noncaloric fat replacements including plant sterol esters that are soluble in such fat compositions. Free fatty acids, vitamin E and tocotrienol have each been utilized by other inventors to promote the solubilization of phytosterols in fats and oils, with the expectation that the cholesterol lowering properties of various phytosterols would be improved.
U.S. Pat. No. 5,244,887 by Straub describes the preparation of a cholesterol-lowering food additive composition with plant stanols, including: (i) an edible carrier such as an oil, monoglyceride, diglyceride, triglyceride, tocopherol, alcohol or polyol, (ii) an antioxidant and (iii) a dispersant or detergent-like material such as lecithin, or other phospholipids, sodium lauryl sulfate, a fatty acid, salts of fatty acids, or a fatty acid ester. Straub cites research showing that 1.5 grams per day of a stanol mixture derived from soybean sterols lowered blood cholesterol by 15% after 4 weeks of therapy, and believes that these stanols are preferred to sterols based upon less stanol absorption from the G.I. tract and better heat stability in air than sterols.
U.S. Pat. No. 5,932,562 by Ostlund, Jr. describes an aqueous micellar mixture of plant sterol and lecithin (in a 1:1 to 1:10 mole ratio) which has been dried to a water soluble powder and which is useful as a food additive for reducing cholesterol absorption.
U.S. Pat. No. 4,195,084 by Ong describes a taste-stabilized pharmaceutical suspension of sitosterols to reduce hypercholesterolemia, in which the suspension includes the plant sterol, a chelator such as calcium disodium EDTA, a surfactant and other ingredients to assure suspension and dispersal of the phytosterol.
U.S. Pat. No. 3,881,005 by Thakkar et al. describes a pharmaceutical dispersible powder for oral administration in which sitosterols are combined with any one of a variety of excipients, and any one of a variety of pharmaceutically acceptable surfactants.
U.S. Pat. No. 6,267,963 by Akashe et al. describes a plant sterol/emulsifier complex that has a lower melting temperature than the plant sterol alone. The complex, e.g., a co-crystallized monoglyceride and plant sterol mixture, is said to facilitate incorporation of the sterol into food products without adversely affecting the texture of the food products.
As indicated above, it has been widely believed that increasing the solubility of phytosterols in fat increases their bioavailability and reduces the dose required to achieve a specified degree of cholesterol reduction. Thus, U.S. Pat. No. 5,502,045 by Miettinen et al., describes the preparation and use of the plant stanol, beta sitostanol, in the form of a fatty acid ester which is readily soluble in an edible oil, to reduce the serum cholesterol level in humans. This technology has been utilized in manufacturing the margarine product marketed under the tradename Benecol®.
U.S. Pat. Nos. 6,031,118 and 6,106,886 by van Amerongen et al. describe similar stanol fatty acid esters but provide different and reportedly improved chemical methods for their preparation. Plant sterols (from soybean oil) have also been interesterified with fatty acid esters to produce the margarine marketed under the tradename Take Control®. Clinical studies suggest that with mildly hypercholesterolemic individuals, dietary intake of between 1.5 and 3 grams per day of the free phytosterol (provided in a fatty acid esterified form) is required to decrease plasma cholesterol approximately 15%.
U.S. Pat. No. 5,932,562 by Ostlund, Jr. points out that cholesterol is absorbed from an intestinal micellar phase containing bile salts and phospholipids which is in equilibrium with an oil phase inside the intestine. Prior to recent experiments, delivery of phytosterol as a solid powder or aqueous suspension was thought to not be preferred because of the limited rate and extent of solubility in intestinal liquid phases. In fact, at least two earlier human studies showed that as much as 9-18 grams of sitosterol per day were required to decrease the plasma cholesterol level by approximately 15% when the sitosterol was provided in a coarse powdered (rather than soluble) form. Yet, esterification of phytosterols, coupled with the use of edible oils to deliver these sterols is not always practical, e.g., in formulating fat-free foods. It is in this context that Ostlund, Jr. provides a water-dispersible mixture of plant sterol and lecithin.
Using a finely milled powdered form of free phytosterols (from tall oil) suspended in a margarine (not fully dissolved or recrystallized in fat), Jones et al. have described cholesterol reduction in hypercholesterolemic humans (Jones et al., Am J Clin Nutr 69: 1144-1150, 1999) and other mammals (Ntanios et al., Atherosclerosis, 138: 101-110, 1998; Ntanios et al., Biochim Biophys Acta, 1390: 237-244, 1998). In these studies, the efficacy based on cholesterol reduction appears to be equal to that of phytosterol and stanol esters reported by others.
Still another method of producing a fine suspension of microparticulate phytosterols in fat and water has been described by Yliruusi, et al. in U.S. Pat. No. 6,531,463. The method involves first heating and dissolving beta-sitosterol in a fat or oil, and then precipitating the phytosterol with water to form a microcrystalline suspension of phytosterol particles in a mixture of fat and water. While this process appears more cost-effective than grinding, emulsification of fat with water causes any fat to become susceptible to oxidation and necessitates refrigeration.
The production of microparticulate phytosterols described in the relevant literature involves increased cost and inconvenience, e.g., the use of grinding, and can result in a mixed emulsified product that is more susceptible to oxidation and rancidity, particularly when an aqueous fat-phytosterol emulsion is involved. In fact, there are limitations and disadvantages inherent in most of the methods of phytosterol preparation and delivery described above. These methods have included grinding, formation of fat and water mixed phytosterol emulsions, chemical modification of phytosterols, e.g., esterification, and mixing of phytosterols with substantial amounts of specialized solubilizing and dispersing agents.
A recent review article entitled “Therapeutic potential of plant sterols and stanols” (Plat et al., Current Opinion in Lipidology, 11: 571-576, 2000) has summarized the results of a number of independent clinical studies in which human plasma cholesterol levels were monitored before and after ingestion of food products enriched with plant sterols and sterol esters (approximately 2-2.5 g per day). The authors conclude that LDL cholesterol levels decreased significantly, i.e., an average of 10-14%, under this regimen.
The description above is provided to assist the understanding of the reader, and does not constitute an admission that the cited references are prior art to the present invention.